[media] siano: add a MAINTAINERS entry for it

Nobody is maintaining this driver. The project started by a
developer that used to work at Hauppauge. A Siano developer
assumed its maintainership after that, but he left the company.
Another Siano developer sent several patches updating it, but,
after upstream feedback, it seems he gave up merging the driver,
as he never answered back to the received feedbacks.
As I have a few siano devices here that work with ISDB-T, I
can help to keep it into a good shape. So, better to take its
maintainership.
I don't have any siano SDIO setup here, trough. So, I'll just
apply without any test any patch that looks sane and touches
only drivers/media/mmc/siano. So, let's tag it as "Odd fixes".

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>